According to a study from March 2015 based on sediment research released on the scientific journal PNAS under the headline “Orbital forcing of climate 1.4 billion years ago”, climate change seems to be forced by variations in earth-solar orbital cycles. These changes happen over thousands of years and they bring ice ages and warming periods distributed over a 100,000-year cycle.
It is not so much the weather on the sun in the form of solar flares and sunspot activity that are decisive for the climate in the long run. Neither so much cosmic background radiation from our own sun and other elements in the universe make up the major changes for the climate. But the earth’s inclination, shape of orbit and distance to the sun are decisive for the long-range climate change we experience on Earth.
The 1.4 billion year old Chinese Xiamaling Formation
The evidence arises from analyses of sedimentary records from the approximately 1.4 billion year old and exceptionally well preserved Xiamaling Formation in China. These Chinese Xiamaling sediments have preserved evidence of repeated climate fluctuations. And it is these repeated climate fluctuations that shows orbital influences at play and that climate change at the time arose as a result of the Earth’s varying inclination and orbit around the Sun.
The Xiamaling Formation in North China Craton, is a set of very old but well-preserved low-mature to mature sedimentary sequences on a passive continental margin. It records the interaction among climate, ecosystem, and dynamic ocean chemistry.
The Milankovich cycles
The sediment study has revealed that the so-called Milankovich cycles that Earth´s climate is affected by today, also affected the climate 1.4 billion years ago, but with a little twist to it. The Moon was closer to earth at that time and probably caused some of the Milankovich cycles to be a little shorter.
The current Milankovich orbital cycles consists of three different time periods – 20.000, 40.000 and 100.000 years. If we look back a million years, research can document that the cycles have caused ice ages with an approximately 100,000 year gap.
According to the sediment research, we are now in a warming period that has lasted for 11,000 years. But parallel to the long 100.000 years climate cycle, there is two other cycles (20.000 & 40.000 years cycles) running. These are responsible for the smaller middle ice ages.
Earth-solar orbital cycles based on three astronomical factors
1). The Earth’s orbit around the Sun (Eccentricity) does not always keep the same elliptical orbit. Sometimes the Earth’s orbit is closer to the Sun, while other times it is further away. In our time, this creates a cycle of 100,000 years and a secondary cycle of 400,000 years. Earth’s eccentricity is very slowly decreasing today and is approaching its least elliptic and most circular orbit around the Sun.
2). The Earth’s axis has a tilt (Obliquity) that changes in relation to the Sun. However, the slope is not constant, but fluctuates between 22 and 24 degrees. The greater the slope, the greater the difference between summer and winter. This cycle lasts in our time 40,000 years.
3). The earth rotates on its own axis (Precession). It gives day and night. Due to the Earth’s elliptical orbit and tilt in relation to the Sun, a cycle of 20,000 years occurs in our time, where there is a difference between whether the Earth is closest to the Sun in summer or winter.
Read more about the Earth-solar orbital cycles here and here
Climate change in the short term
Earth’s spin, tilt, and shape of orbit are those three specific factors that affects the amount of solar energy received. They are the basic mechanics behind long-term climate change. When the solar energy we receive is at maximum we are in a warm period. When it´s at minimum we have an ice-age.
Climate change in the short term is a much more volatile topic to tackle. There can be many different factors at play, both natural causes and human imposed causes.
The natural climate change can be caused by several things such as El Nino and La Nina, volcanic eruptions, asteroid strikes, solar flares and variations in the cosmic background radiation.
The human imposed climate change is the big topic of discussion. Do we have human imposed climate variations or is our influence on the climate so insignificant that it is not worth mentioning?
Well, worth to mention is the massive weather modification by commercial air traffic that creates artificial clouds and emits a layer of carbon-dioxide (CO2) in the upper troposphere that has been going on for decades. If there is anything from the human race that affects the climate and the weather it must be this.
Sources
PNAS: Orbital forcing of climate 1.4 billion years ago link
SDU: Same forces as today caused climate changes 1.4 billion years ago link
ResearchGate: The Chinese Xiamaling sediments link
NASA: The Milankovitch (Orbital) Cycles link
UGC Berkely: Earth’s spin, tilt and orbit link